<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8" />
		<title>test</title>
	</head>
	<body>
		<script type="text/javascript" >
			let arr = [1,3,5,7]
			let arr2 = [2,4,6,8]

			let originalPush = Array.prototype.push

			originalPush.call(arr,9) //相当于写了 arr.push(9)
			originalPush.call(arr2,10) //相当于写了 arr2.push(10)

		</script>
	</body>
</html>